Lost accuracy

[haptoshoot]

I originally posted this in the 100-300 forum. I thought it was probably better as its own thread.

My savage MKII TR was consistently shooting in the mid 240's to high 240's at 100yds I'm now getting 5-6 inches of verticle stringing and 1-2 inches of lateral spread. =( . Same ammo, same lot, nothing in the equipment or shooting routine has changed. I've checked everything mechanical. Even looked at the stock with bright light and magnifying glass. Rifle is pillar bedded with 1/8 bottom metal, It likes 23 and 18 inch pounds on the screws. Groups with my 10/22 and 308 have actually gotten better so I don't think its me.

Just for grins I tested some ammo I had laying arround. In the past SK + has always produced great results at 50, 100 and 200 yards, with Wolf Match a close second. Federal Match never shot well and Rem subsonic was ok. Yesterday at 50yards federal was the best at just over 1", Rem Subsonic next with a vertical spread of 3" and SK + was a great pattern for an improved choke from a shotgun. I am soooooo confused.

I cleaned and lubed the chamber, trigger, and bolt, no improvement. Then I moved a Nikon 4-16 X 50 tactical from my 308( that is shooting under .5 MOA), no improvement.

I cleaned it yesterday, reseasoned the barrel with 25 shots. Today with zero wind groups tightened up but not back to where they were. 2.5 inches of vertical spread and 2 inches of lateral spread at 100. At 50 the groups are 1.5- 2 inches. roughly double what they were before I lost accuracy.

Muzzel crown?

HELP ! I am so open to suggestions.

 

[RFtinkerer]

Re: Lost accuracy

Did it lose it suddenly, like one day it was shooting MOA, next it was shotgunning? Did you not shoot it for a long time, or was this just a recent change? Are you ABSOLUTELY sure you changed NOTHING? I probably will not be able to help you, but make sure you give a timeframe and any changed conditions (even season) to help exercise your brain and maybe someone else's here.

 

[clodhopper]

Re: Lost accuracy

Could it be Temprature related?

 

[Aquatic_Robotic]

Re: Lost accuracy

I a not totally familiar with the type crown your Savage has, but IMO it would be odd that the crown just "went bad" unless it has been damaged. Most of todays quality 22 lr barrels should go 10,000's of rounds and not have muzzle crown issues.

Sounds like you gave it a good cleaning and re-seasoned the barrel. Did you check the chamber to be sure you don't have "build up" in that area. I have 1,300 rounds through my Annie 64 since the last full barrel cleaning and have not put anything down the barrel, but a dry patch. I do clean the bolt and chamber after every range session and notice my chamber gets pretty gunked up if I fire more than a couple 100 rounds in one session.

I would check the muzzle crown for damage, inspect the chamber area closely for any build up you might have missed. Do you notice any tightness when you chamber a round, as compared to the past?

One last thought. I had a rifle a few years ago that was just a tack driver and from one hunting season to the next it just went to crap. I tried everything I could think of just like you are doing. I even changed out scopes as well and nothing helped. I was about to give up on the gun and for some reason I checked the torque on my scope "bases" and found one of the screws on my rear base was actully broken. I took off the bases, remounted with new screws and all was back to normal.

Hope this helps and good luck with it.

 

[PRDRIVER]

Re: Lost accuracy

I second Aquatic Robotic advice to check the scope base. I had a similar thing happen to me on a 10/22 a few years a go.

 

[Situation Normal]

Re: Lost accuracy

Any chance that the barrel/action is no longer centered in the stock? If the barrel channel was not opened wide enough, the barrel may be rubbing against the stock and no longer free floated.

It may be worth while looking to see if the front sling stud is protruding into the channel as well. I recently picked up a CZ trainer and found during the first disassembly the the sling stud from the factory was through the channel and pressing on the bottom of the barrel.

Look at your pillar too. It may have come loose.

 

[RTH1800]

Re: Lost accuracy

Could be a carbon ring issue. Do you have a bore scope?
I am thinking that will tell the tail. Look on bottom of bore in front of chamber.
Good luck.
RTH

 

[haptoshoot]

Re: Lost accuracy

No access to a bore scope. Using what I have at my disposal I can't really see well. Dental mirror, dental pick, and flash light. ..... I finally found a use for Dads old dental intruments. My wife was a little concerned that I was giving my rifle a Dental exam! What exactly am I looking for when checking for a carbon ring?

I removed the action from stock, checked and retorqued with torque wrench every single screw, reinstall stock and scope. yes the base is tight..... No improvement,

Then I remembered that my ammo testing was in Oct and all groups were fired from then until I had surgery in March. After a two month layoff during recovery it dosen't shoot worth a damm. Could 25 degrees have that much effect on the ammo. Most groups were shot between 15 - 50 degrees this winter. All shooting recently has been 68-80 degrees.

This is the only thing I can think of. =(. I'm going to order bunch of match ammo and go through testing ammo again.

 

[RTH1800]

Re: Lost accuracy

Hap,
I think you will be wasting your time and money on ammo until the problem is located. I suspect the bore. A few years ago there was an article in Precision Shooting about carbon rings and what to do about them, how to detect them etc. By Bill Calfee. If you call PS, they can likely get you a copy, I would guess. I think you might feel it with a tight, lubed patch. I also suspect a bore scope would be near by as they are quite common now. Rimfires are notorious for falling of accuracy, and carbon is the most likley cause. It tends to build up just in front of the chamber, on the bottom side more than the top. It can be in other places as well. I do not think temp is a big factor, IMO it could cause slight problems but not huge shifts.
There are many rimfire experts on this site and all would know more than I about this, suprised no input yet. Good luck .

 

[former naval person]

Re: Lost accuracy

Clean it good with a carbon solvent...GM Top Motor Cleaner is good to go. Let it soak in and brush it out. A little Flitz on a patch back and forth in the throat area. Clean that out with solvent and reseason with 50 to 100 rounds of the favorite. I suspect that the prolonged set up without firing may have solidified the ring mentioned. JMHO

 

[Gruff]

Re: Lost accuracy

Could be as simple as inconsistent firing pin strikes. Clean the bolt really good with lighter fluid, charcoal lighter, or mineral spirits (it's all just different grades of mineral spirits). Also. check the breech end of the barrel for buggers, especially if you dry-fire (a no-no for rimfires without a snapcap).

 

[Greg Langelius *]

Re: Lost accuracy

As .22's get used, they tend to accumulate a ring of lead fouling at the very front end of the chamber. Periodically removing this (and it can be difficult) can restore new-gun accuracy. Shooter's Choice makes a Lead Remover product that penetrates beneath and soaks it loose. I have also borrowed a .22lr chamber reamer and used it (very springly/cautiously) to chase out the lead ring.

Greg

 

[TOP PREDATOR]

Re: Lost accuracy

i've used it, it gets rid of alot of stuff in the barrel / chamber. easy and simple to use, worth a try.

http://www.shooters-choice.com/lead_remover.html

groups / accuraccy can be affected by temperature, humidity, etc. either by swelling or contracting the stock and such, but from 1" to 2" to 5" to 6" is a bit extreme.

Effects of ammo temperature itself - not air temp

POA / POI change with temp - demonstration

maybe the time off had something to do with it or whatever the surgery was to, may have screwed up your foundation.

i'm going through a loss of accuraccy thing too with my MKII BV, i don't believe it's me (making sure to use a good rest / rear bag, not just bipod). everything is tight, it may be a scope going bad in my instance. i have some vacation time coming up, will probably narrow it down in a few weeks.

i wish you luck in finding out what's up with your rig.

 

[haptoshoot]

Re: Lost accuracy

Thanks for all the input.

I'm going to try to find a bore scope and look at chamber for lead/carbon ring.

I don't think its me .....I'm seeing good groups and improvemnt with my 308 and 10/22 at both distance and position shooting.

 

[haptoshoot]

Re: Lost accuracy

No bore scope yet.

I did a limited ammo test today. 20 shots of each ammo measuring the last 5 as a group. used dry bore snake one pass between each type of ammo.

I know this is not true testing I just wanted an indication if there could be any improvement with changing ammo.

tested ten ammo types. Eley Club and Green tag were head and shoulders tighter than all others. SK + which was always the best. Is now the worst....

Eley seemed to settle in after only five shots. the other 15 were just under .5inch. Green tag took 10-15 shots to settle in and the last 5 were .5 inches. My 10/22 also likes Eley Club

After checking chamber and muzzle crown I will retest this ammo. I'm excited about Eley. Would it be dangerous to asume that Team and Match will also shoot well?

 

[Shortdraw]

Re: Lost accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: haptoshoot</div><div class="ubbcode-body"> Eley Club and Green tag were head and shoulders tighter than all others.................Would it be dangerous to asume that Team and Match will also shoot well? </div></div>
Don't discount the green tag, my Anschutz likes it the best out of everything I've tried and seems to be quite consistent for econo-ammo. Eley Club bay shoot very good and the Team and Match not, just have to try them out. My Anschutz shot Tenex, Lapua Center-x and Midas not so well and it's some of the most expensive and consistent ammo out there. It's all about the harmonics, how well it fits the chamber, and consistency of the charge and primer.

 

[haptoshoot]

Re: Lost accuracy

Success. I could not see any carbon ring or damage to the crown. Having nothing to lose I used a lee case deburing tool to clean the muzzel crown and then buffed with pointed pad on my dremel.

Groups are almost back to where they belong. Now the margine for error is such that it might be the driver. Will have to shoot it a couple more times to see.

Sk+ is shooting well again and I found out that the rifle also likes Eley to I will be testing that too

Thanks for all the sugestions

 

[Situation Normal]

Re: Lost accuracy

Congrats Hap! Glad to hear that you got it figured out.